Power supply systems generate electrical or mechanical power to drive machine elements, producing useful work. Fuel cells have been used as a power plant in many power supply systems. For example, fuel cells have been proposed for use in electrical vehicular power plants to replace internal combustion engines (ICE's).
Fuel cells generate electricity that is used to charge batteries and/or to power an electric motor. A solid-polymer-electrolyte fuel cell includes a membrane that is sandwiched between an anode and a cathode. To produce electricity through an electrochemical reaction, hydrogen (H2), is supplied to an anode side of the fuel cell and an oxidant, such as oxygen (O2), is supplied to a cathode side of the fuel cell. The source of the oxygen is commonly air.
Besides fuel cells, other power supply systems have been developed and are currently being developed that process H2. For example, an ICE has been developed that processes H2 to provide drive torque.
Because H2 is required to generate power, on-board H2 storage systems are a focus of research and development. Traditional H2 storage systems include pressurized tanks of gaseous H2 or cryogenic liquid H2 and adsorption/absorption of H2 on or into exotic material. Cryogenic liquid H2 storage includes the potential of H2 loss during extended periods of storage. Both pressurized and cryogenic H2 storage require sophisticated and expensive materials and support systems. Significant energy is associated with depositing and/or extracting H2 in an adsorption/absorption H2 storage system.